1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to apparatus for correcting out of tolerance "between guide" dimensions of the guide rails in an elevator system.
2. Description of the Prior Art
One of the most important dimensions in an elevator system is the between guide (BG) dimension, which is the horizontal dimension between the guide rails which guide the elevator car in its vertical travel path. The BG dimension must be maintained within a predetermined tolerance in order to achieve a smooth ride without objectionable sway of the elevator car.
The guiding structure for an elevator car includes first and second horizontally spaced, vertically oriented guide rail assemblies, each comprising a plurality of elongated, T-section guide rail members disposed in end-to-end relation.
Brackets are fastened to the associated building, and the guide rail members are fastened to the brackets via rail clips. Out of tolerance BG dimensions at the brackets may be corrected by shimming.
The guide rails are straight when manufactured, but they may become bowed during storage, shipment and installation due to stresses being relieved during this time period. The rails may also become bowed after installation such as by operating a construction hoist on the rails during construction of the building. It is often difficult to achieve the desired BG dimension by shimming at the brackets, and the present trend in building construction has added to this difficulty. The weight of the steel used in a modern building is being reduced by more thorough engineering. While the amount of steel used is adequate for the loads imposed upon the building by the elevators, it does not provide the rigidity previously available at the rail bracket attachment points. This more flexible building structure makes it more difficult to realign the elevator guide rails and to correct BG dimensions that are out of tolerance. The difficulty is compounded when the rail joint, i.e., the joint between adjoining guide rail members, is not close to a bracket.
The guide roller assemblies on the elevator car which co-act with the guide rails to guide the elevator car must be adjusted for the smallest BG dimension encountered over the travel path. If this smallest BG is the result of a substantial bulge, the guide roller assembly may not properly contact the guide surfaces on the guide rails at the widest BG dimension.